Volatile liquid inhalation anesthetics are known in the art and include by way of example halothane, trichloroethylene, and halogenated ether derivatives including enflurane, fluroxene, methoxyflurane, isoflurane and 2-(difluoromethoxy)-1,1,1,2-tetra-fluoroethane.
The latter two inhalation anesthetics have received much attention because they provide a rapid rate of recovery and therefore are particularly suitable for administering to patients during outpatient surgery.
The most common method of preparing isoflurane (CHF.sub.2 OCHClCF.sub.3) is by the reaction of trifluoroethanol (CF.sub.3 CH.sub.2 OH) and chlorodifluoromethane (CF.sub.2 HCl) in the presence of an organic base to produce a compound of the formula CHF.sub.2 OCH.sub.2 CF.sub.3 which is then reacted with chlorine gas in the presence of light energy and optionally an organic solvent to thereby obtain isoflurane.
2-(difluoromethoxy)-1,1,1,2-tetrafluoroethane (hereinafter referred to as "CHF.sub.2 OCHFCF.sub.3 ") is most commonly produced by reacting isoflurane with a fluorinating agent such as BrF.sub.3. The production of CHF.sub.2 OCHFCF.sub.3 is largely dependent on the starting materials used to prepare isoflurane.
The starting material, trifluoroethanol, is both difficult to produce and expensive to obtain. Use of this starting material therefore significantly increases the cost of producing both isoflurane and CHF.sub.2 OCHFCF.sub.3.
It is therefore an object of the invention to provide methods of producing isoflurane and CHF.sub.2 OCHFCF.sub.3 from inexpensive starting materials.
It is a further object of the invention to employ novel intermediate compounds for the production of isoflurane and CHF.sub.2 OCHFCF.sub.3.